Magnetic tapes

ABSTRACT

Aqueous dispersion coatings as binders for magnetic particles in the manufacture of audio, video and data processing magnetic media.

FIELD OF INVENTION

This invention pertains to magnetic media and the process of makingsame.

BACKGROUND OF THE INVENTION

Many patents have been issued pertaining to the manufacture of magneticmedia such as audio tape, video tape, floppy discs and hard discs forcomputers and the like. Such giants of industry around the world asThree M Company and Ampex in the U.S.A., B.A.S.F. in Germany and Sony,JVC and Fuji in Japan are among the many companies producing suchproducts.

In all the products being currently produced organic solvent systems areemployed. Today's health and safety requirements greatly add to the costof these magnetic media due to the implementation of solvent recoverysystems. Also the loss of solvent due to volatilization, if there is norecovery system, is not only a health hazard to workers, but is of greatexpense to the manufacturer; and the fire and explosion hazard whicheffects insurance costs. Air pollution prevention means, such asscrubbers for removal of organic vapors are high in cost.

There is a need, therefore, for a mechanism to reduce such addedmanufacturing costs. Such a procedure is found in the instant inventionwhich eliminates the use of organic solvents.

It is an object of this invention to provide a binder system formagnetic particles that is free from organic solvent.

It is another object to provide a binder system for magnetic particlescomprising an aqueous dispersion.

Yet another object is to provide a water based binder for magneticparticles that gives rise to excellent adhesion between said particlesand the coating substrate (base).

It is a yet further object to prepare a water based dispersion magneticmedia that is suitable for full range recording and reproduction.

A still further object is to provide lower cost, high quality magnetictapes for audio and video and computer useage as well as floppy andrigid metallic discs.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such steps with respect to each of theothers and the products possessing the features, properties and relationof elements which are exemplified in the following detailed descriptionand the scope of the application of which will be indicated in theappended claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description.

KNOWN PRIOR ART

Applicant is aware of U.K. Pat. No. 482,897 assigned to I. G. FarlenIndustries in 1938. This patent described the function of methylolderivatives of acrylamide and methacrylamide and their respectivepolymers and copolymers. The products of the reference are significantlydifferent from those prepared herein in that the end products are a heattreated, cross linked, insoluble end product.

SUMMARY OF THE INVENTION

Coating compositions are disclosed for application upon a suitable basematerial for the preparation of magnetic tapes, magnetic films andmagnetic discs for the recording of information. The coating isdeposited on the film from an aqueous dispersion rather than from anorganic solvent.

DESCRIPTION OF THE PREFERRED EMBODIMENT

There are many known disadvantages to the deposition of magnetic filmsfrom an organic solvent system. These have been touched on brieflyelsewhere herein. When employing the processes disclosed herein however,and the compositions made according to such processes, most if not allof the disadvantages of the solvent based systems can be overcome. Theonly effluent is water, and in most locations in this country and inother nations, this is not detrimental.

I have found that there are many polymer latices, which when mixed withcertain other ingredients, which will be described below, can be used asthe main binder for an aqueous based magnetic coating formulation. Thesevarious latices include but are not limited to styril, acrylic, vinyl,carbamo, and other main moiety based latices all of which are capable offorming self supporting films. Typical examples of these latices includethe following;

Rohm and Haas Rhoplex E-=358

Union Carbide UCAR 366

Union Carbide UCAR 503

Witco Witcobond W-290H

Witco Witcobond W-234

Mobay Impranil DLH

Goodrich Hycar 26091

Goodrich Hycar 26106

Goodrich Hycar 26138

Goodrich Hycar 1577

The first four are relatively soft films, useful in the manufacture ofcomputer and audio media, while the remaining are relatively harder andare suitable for video or high density disc recording.

The above enumerated latices and dispersions and others when employedalone do not provide adequate adhesion characteristics to produce auseful magnetic particle binder, be the particle metal or metal oxide.They must be used in conjunction with a two part additive systemhereinafter designated Additives A and B respectively.

Unfortunately, there is no empirical formula for the latices that can beemployed in my invention. This is readily seen from the fact thatvarious naming groups can be associated with the polymers employableherein. To be deemed satisfactory ingredients for use in the instantprocess, the magnetic particle containing films formed from any givenpolymer must satisfactorily pass a plurality of evaluation tests. Thesetests are applied not to the basic polymer films but to the endproducts. Thus when a film forming material is used as a binder formagnetic particles, it must be capable of passing an adhesive tape test,a scratch test, and a crease test. If the end product cannot pass thesetests, then the polymeric material is deemed unsatisfactory for theinstant technique.

To further complicate the situation, it is seen even the process ofmaking the latex can contribute to its compatibility or lack thereofwith Additives A and B. Thus I have found that slightly basic polymercompositions tend to have a better chance of Additive compatibility thando acidic ones.

What I have found therefor is the fact that certain polymer latices whencombined in the manner to be described below, with Additives A and B,along with surface active agents, defoamers, lubricants, and other"finishing" agents, can when mixed with magnetic particles yield a filmforming composition with sufficient binding of the magnetic particles(metal or metal oxide) to the coating substrate to yield an acceptablemedia in the format of tape and discs for the recording of information.

ADDITIVE A

A wide variety of compounds are useful as the "Additive A". In generalthese are monomeric compounds or mixtures thereof. Compositions fallingwithin the formula have the property of being water soluble or at leastwater dispersable as well as providing a plasticizing effect on theunderlying polymer of the commercial latex as well as plasticizingeffect on Additive B. The compounds correspond to the general formula:##STR1## where Y may be H, CH₃ --, C₂ H₅ --, ##STR2## wherein Z is F orCl.

P may be represented by polyhydroxybenzene compounds such as, but notlimited to, catechol, resorcinol, hydroquinone, t-butyl catechol,hydroxethylresorcinol, among others. P may also be a substituted orunsubstituted o, m or p aminophenols or aromatic diamines. Typicalexamples include ##STR3## wherein X is represented by H--, CH₃ -- orHOCH₂ CH₂ -- and Y is as defined above.

ADDITIVE B

Additive B is a complex water soluble or water dispersable polymer whichhas at least five percent (5%) of its monomeric constituents derivedfrom acrylamide or methacrylamide. The remaining approximatelyninety-five percent (95%) of the monomers units may be one or more ofany vinyl monomer, which is copolymerized with the acrylamide ormethacrylamide to yield a water soluble or water dispersable system.This copolymerizate must be further condensed first with formaldehydeand then with any of the polyhydroxy aromatics, aminohydroxy aromaticsor diamino aromatice designated as a "P variety" as disclosed underAdditive A, above, to yield the final Additive B polymer. Its formula isset forth below: ##STR4## The grouping: P--CH₂ -- must be substituted tothe extent of at least five percent (5%) of the total monomeric units inthe polymer chain, and up to as high a value as will still yield a watersoluble or water dispersable system. This may be anywhere from fivepercent (5%) to ninety-five percent (95%) depending upon the systeminvolved. However, I have found that the most generally useful materialshave a degree of substitution of from twelve percent (12%) to sixty-fivepercent (65%) and I prefer to use a degree of substitution of fromtwenty percent (20%) to thirty-five percent (35%). Also I prefer thatthe monomeric constituents of acrylamide or methacrylamide in thepolymer backbone be greater than fifty percent (50%).

Previously I mentioned that I was aware of British Pat. No. 482 897,which describes the formation of methylol derivatives of acrylamide andmethacrylamide and their respective polymers and copolymers. The claimsin this patent are for a heat treated product which yields across-linked insoluble end product.

Contrarily, for my invention I require only to partial substitution ofthe polymeric amides and only the degree that water solubility or readywater dispersability and swelling is retained.

The following specific examples shall be considered as exemplary of theinstant invention. In the first example the term deionized water isutilized. In all the appearances of the word water, it shall beunderstood that deionized water, i.e. water with a low salt content iscontemplated.

PREPARATION OF ADDITIVE A (Adhesive Plasticizer) EXAMPLE 1A

Condensation of Resorcinol with N-Hydroxymethyl Acrylamide

To 15 g of a commercial 48% N-hydroxymethyl acrylamide was added 15 gdeionized water. Thus diluted the solution had a pH of about 4. Then0.15 ml of 10% sodium hydroxide was added, to raise the pH to 8.5-9.Then 9 g of solid resorcinol was added all at once with stirring. Thesolution was endothermic and upon completion of the addition the pH haddropped back to 4. Addition of 7 ml NaOH brought the pH back to 8.5-9.After allowing the reaction mixture to age overnight it was ready foruse.

EXAMPLE 2A

Condensation of Catechol with N-Hydroxymethyl Acrylamide

In a beaker containing 30 g of 48% N-hydroxymethyl acrylamide was added30 g water. This solution was made alkaline with 0.3 ml 10% NaOH, priorto the addition of 18 g solid catechol. The solution and reaction of thecatechol was endothermic and was aided by heating the beaker on a waterbath at 50°-60° C. for about ten (10) minutes. After standing one hour15 ml more 10% NaOH were required to bring the pH back up to 8.5. Afteraging overnight the reaction mixture was ready for use.

EXAMPLE 3A

Condenstaion of t-Butyl Catechol with N-Hydroxymethyl Acrylamide

To 10 g 48% N-hydroxymethyl acrylamide was added 10 ml water and 0.1 ml2.2N NaOH. Then 8 g solid t-butyl catechol was added with stirring whileheating on a warm water bath. Two layers were obtained but afteraddition of 1.5 ml 2.2N NaOH the mixture became clear and formed ahomogeneous solution (pH 8.5-9). The mixture was bottled and allowed toage overnight prior to use.

EXAMPLE 4A

Condensation of m-Aminophenol with N-Hydroxymethyl Acrylamide

To a solution of 4.9 m-aminophenol in 25 ml hot water was added 7.5 ml48% hydroxymethyl acrylamide. The reaction mixture was allowed to coolin a stoppered brown bottle and aged twenty-four (24) hours prior touse.

EXAMPLE 5A

Condensation of m-Toluene Diamine with N-Hydroxymethyl Acrylamide

To a solution of 6.1 g m-toluenediamine in hot water (16 ml) was added10.5 ml 48% hydroxymethyl acrylamide. Upon cooling the reaction mixturewas bottled and stored overnight prior to use.

PREPARATION OF ADDITIVE B (Adhesive Polymers) Introduction

In the following examples an acrylamide polymer was selected which mettwo criteria. First, that it could be dissolved in a sufficiently highconcentration to yield a reasonable working viscosity; and at the sametime there would be provided sufficient residual mass for incorporationwith commercial latices to yield optimum adhesion characteristics. Apolymer system which satisfies these requirements is AmericanCyanamide's Cyanomer P-26. It contains some 4 to 6% acrylic acid as acopolymer with the acrylamide. The reactions carried out in thefollowing examples are schematically shown as follows: ##STR5##

In order to retain aqueous solubility in most cases only about 25% ofthe amide groups were substituted with the methylene polyhydric phenols(ie. resorcinols, catechols, hydroquinones) or the methylene aminoaromatics (ie. aminophenols, diaminoaromatics), as will be seen below.

EXAMPLE 1B

Preparation of Adhesive by Resorcinol Condensation

In a beaker of 160 ml of H₂ O, 20 g of Cyanomer P-26 was slowly addedwith mechanical stirring to make sure that complete solution occured.The initial pH was around 5. The addition of 2.5 ml of 1.77N NaOHbrought the pH up to 8.5. Then 4.2 ml of 37% formaldehyde solution(enough to replace 25% of the amide groupings) was added and within afew minutes the pH had dropped back to 5. It now required 14 more ml1.77N NaOH to bring the pH back up to 9 and hold this value for onehour. After such, 5.75 g solid resorcinol was added with stirring. Allthe resorcinol dissolved to yield a clear solution. The pH dropped backto 8. It then required 15 ml more 1.77N NaOH to bring the pH back up to8.5. At this point the solution turned from clear to milky opaque. Themixture was bottled and allowed to age overnight before use.

EXAMPLE 2B

Preparation of Adhesive--Resorcinol Condensation

(Reverse Addition)

It was found that on a number of occasions tha preparations of adhesive(Additive B) made according to Example 1B would gel shortly afterpreparation. By carrying out the addition with resorcinol in a reversemanner a free flowing mobile solution was obtained with goodreproducibility from batch to batch.

In a beaker, 20 g of Cyanomer P-26 was slowly added to 120 ml water withmechanical stirring. When that solution was complete a measurement wasmade of the initial p". It was about 5. Then 4.2 ml 37% formaldehydesolution was stirred in followed by 10 ml 2.2N NaOH to bring the pH upto 6. An additional 7 ml of NaOH was required to raise the pH to 10.After standing one hour the viscous mixture was stirred slowly in a thinstream into a solution of 6 g of resorcinol dissolved in 40 ml water. Atthe end of the addition the pH had dropped to 7.5. The solution required2 ml of 2.2N NaOH to bring the pH back up to 9. The greatly thinnedreaction mixture was bottled and stored overnight prior to use.

EXAMPLE 3B

Preparation of t-Butylcatechol Substituted Adhesive

20 g Cyanomer P-26 was dissolved in 160 ml water with good mechanicalstirring. The solution required 6.5 ml of 2.2N NaOH to raise the pH to8.5-9. To this was added 4.1 ml of 37% formaldehyde and the reactionmixture again became acidic. After standing ten minutes, 9 g oft-butylcatechol was added to yield a milky dispersion. This was followedby 10 ml 2.2N NaOH to bring the pH to 7.5. The dispersion darkened andafter fifteen minutes more stirring the pH had dropped to 6-6.5. Anadditional 2 ml of the NaOH was added to raise the pH to 8.5. Thisproduct was bottled and stored prior to use.

EXAMPLE 4B

Preparation of m-Aminophenol Substituted Adhesive

Using a Mixmaster®, 20 g of Cyanomer P-26 was slowly added to 120 ml ofwater to yield a somewhat viscous solution. The pH was about 5 and afterthe addition of 3.5 ml 2.2N NaOH it was raised to 6.5. Then 4.2 ml of37% formaldehyde was stirred in and the pH immediately dropped back to5. Additional 2.2N NaOH was added incremently until a total of 15 mlbrought the pH up to 10. During this time and after standing one hourthere was an appreciable increase in viscosity. At the end of the hourthe mixture was neutralized by the addition of 6.5 ml of 0.5N HCl to pH7-7.5.

In a separate bowl, 6 g of m-aminophenol was heated with 40 ml water to60°-65° C. until it was all in solution. This solution was then wellstirred while the polymethylolacrylamide solution was slowly added in athin stream. A clear semi-viscous solution resulted having a pH 8. Thiswas bottled and used in subsequent coating formulations.

EXAMPLE 5B

Preparation of m-Toluene Diamine Substituted Adhesive

The preparation of this formulation was identical to that of Example 4Bexcept that 6.3 g of m-toluene diamine was used in place of the 6 g ofm-aminophenol.

PREPARATION OF COATINGS

In general, laboratory batches of coatings formulations were prepared inthe following manner:

A requisite amount, as determined by the skill of the art, of magneticiron oxide was placed in a glass mortar and to this was addedsurfactants, Additives A and B and water. This mixture was well groundwith a glass pestle until a smooth creamy paste was obtained. Aproportional amount of commercial latex (or mixture of latices) wasadded to the paste along with more water and an optional anti-foamingagent. This total mixture was again ground to a very smooth flowabledispersion. The paste was then spread over a film of polyester by meansof a doctor blade, allowed to air dry several hours, it was finish driedin an oven at about 85°-90° C. Adhesive characteristics were checked bymeans of the adhesive tape test, folding and creasing and scratching andlifting with an Xacto® blade. The coatings, as described in thefollowing examples, responded very well to the tests described above andare useful in the preparation of high quality magnetic coatings.

When magnetic iron oxide was used the following general formulation and

5.0 g Magnetic iron oxide

4 ml water

0.1 ml Aerosol OT

0.1 ml MAZAMIDE 80

0.35 ml Additive A--from the above

0.8 ml Additive B--from the above

Grind to a smooth paste

x ml Commercial Latex wherein x varies between about 1.5 to 2.0 ml

4 ml water

0.05 Surfynol 104A (or other anti-foam known to the art)

Grind and coat.

The coatings prepared according to the above formulation are summarizedin Table I and which are designated 11-22, since 1-5 A and 1-5 Brepresent 1-10.

                  TABLE I                                                         ______________________________________                                        Exple                                                                         #     Additive A   Additive B Latex                                           ______________________________________                                        11    Resorcinol-  Resorcinol-                                                                              1.8 ml Rhoplex E-358                                  Ex. 1A       Ex 1B                                                      12    Resorcinol-  Resorcinol-                                                                              1.8 ml UCAR 503                                       Ex. 1A       Ex 2B                                                      13    Resorcinol-  Resorcinol-                                                                              1.8 ml UCAR 366                                       Ex. 1A       Ex 2B                                                      14    Resorcinol-  Resorcinol-                                                                              1.5 ml Rhoplex E-358                                  Ex. 1A       Ex 2B      0.5 ml Gen Tac (a)                              15    Resorcinol-  Resorcinol-                                                                              1.5 ml UCAR 503                                       Ex. 1A       Ex 2B      0.5 ml Gen Tac (a)                              16    Resorcinol-  Resorcinol-                                                                              1.5 ml UCAR 366                                       Ex. 1A       Ex 1B      0.5 ml Gen Tac (a)                              17    Catechol-Ex. 2                                                                             Resorcinol-                                                                              1.5 ml Rhoplex E-358                                               Ex 1B                                                      18    "            Resorcinol-                                                                              1.5 ml Rhoplex E-358                                               Ex 2B      0.5 ml Gen Tac (a)                              19    "            t-Bu Catechol                                                                            1.8 ml Rhoplex E-358                                               Ex 3B                                                      20    Resorcinol   t-Bu Catechol                                                                            "                                                     Ex 1A        Ex 3B                                                      21    t-Bu Catechol                                                                              Resorcinol "                                                     Ex 3A        Ex 1B                                                      22    t-Bu Catechol                                                                              t-Bu Catchol                                                                             "                                                     Ex 3A        Ex 3B                                                      ______________________________________                                         (a) Gen Tac  General Tire's vinyl pyridine rubber latex                       Rhoplex is a trademark of Hohm & Haas                                         UCAR is a trademark of Union Carbide                                     

EXAMPLES 23-25

These experiments were conducted using higher ratios of magnetic oxidethan those in Examples 11-22. Holding all the other ingredientsconstant, the amounts of magnetic iron oxide were increased to 5.5 g,6.0 g and 7.0 g. The first two films still provided good adhesivecharacteristics but the preparation containing 7.0 g of magnetic ironoxide was somewhat dry and not as smooth.

USE OF HARDER POLYMER LATEX SYSTEMS

In the following examples latices were used whose polymers have a highmodulus and therefore more applicable for use in video tapeformulations. However, while the latices used above had a total solidscontent of about 55-60% many of the following range in total solids from30 to 50%. Therefore adjustments were made in the volume of polymerlatex used and the additional water added. In these examples the amountof magnetic iron oxide was increased to 5.5 g as compared to the 5 gused in the previous experiments.

A typical formulation and procedure is as follows:

Mix 5.5 g magnetic iron oxide

4 ml water

0.1 ml Aerosol OT

0.1 ml MAZAMIDE 80

0.35 ml Additive A (Resorcinol)

0.8 ml Additive B (Resorcinol)

Grind to a smooth paste

x ml Commercial Latex(s) where x varies between 2.0 and 3.3 ml

y ml water

0.05 ml anti-foam

Grind and coat

Aerosol OT and MAZAMIDE 80 are trademarks of American Cyanamid and MazerChemical Company respectively.

All of the coatings prepared in this manner as described in Table IIgave good adhesion by the standard tests.

                  TABLE II                                                        ______________________________________                                                                         Vol.                                         Exple # Vol. Latex Used          Water                                        ______________________________________                                        26      3.3 ml Witco Polyurethane W-234                                                                        2.5   ml                                     27      2.5 ml Mobay Polyurethane Impranil DLH                                                                 3.5                                          28      2.0 ml Goodrich Hycar 26091                                                                            3.8                                          29      2.0 ml Goodrich Hycar 26106                                                                            3.8                                          30      2.0 ml Goodrich Hycar 26138                                                                            3.8                                          31      2.0 ml Goodrich Hycar 1577                                                                             3.8                                          ______________________________________                                    

In a video tape formulation there are far more stringent requirements onthe magnetic oxides as well as the polymer binder. In general special,surface-energized ferrites are used in such formulations when a typicalferrite as supplied by Hercules Powder Company was tested in the aboveformulations, while excellent wetting was achieved, the flowcharacteristics leave much to be desired. By replacing the Aerosol OTand MAZAMIDE 80 (Mazer Chemical) combination of surfactants with systemscomprising 0.05 ml of Nopcosperse 44 (Diamond-Shamrock), 0.05 ml MAFO13, MOD 1 and 0.05 ml MAZAMIDE 80 in the formulations of Table II, using5.5 g magnetic ferrite in place of magnetic iron oxide, excellent filmcoatings were achieved.

Another surfactant combination that works well with the formulations inTable II is a combination of 0.05 ml Nopcosperse 44, 0.05 ml GAFAC 610(GAF Corporation) and 0.05 ml Aerosol OT.

Silicone surfactants such as those manufactured by Union Carbide, havebeen found to produce useful coating dispersions with the polyurethanesystems listed in Table II. However, Silwet L-7600 and L-7602 are bestused alone, without the aid of other surfactants or dispersants.

EXAMPLE 32

Use of Additive B Based on m-Aminophenol

Mix

5.5 g Magnetic Ferrite

4 ml water

0.10 Mopcosperse 44

0.05 ml MAFO 13, MOD 1

0.05 ml MAZAMIDE 80

0.35 ml Additive A (resorcinol, Ex. 1)

0.8 ml Additive B (m-aminophenol, Ex. 4B)

Grind to a smooth paste

2.0 ml Hycar 1577

3.8 ml water

Grind and cast to a tape with excellent adhesive tape, crease andscratch resistance.

EXAMPLE 33

Use of Additives A and B Based on m-Toluene Diamine

Mix

5.5 g Magnetic Ferrite

4 ml water

0.05 ml Nopsocperse 44

0.05 ml MAFO 13, MOD 1

0.05 ml MAZAMIDE 80

0.35 ml Additive A (m-Toluene Diamine, Ex. 5)

0.8 ml Additive B (m-Toluene Diamine, Ex. 10)

Grind to a smooth paste

2.0 ml Hycar 26138

3.8 ml water

Grind and cast to yield a film having good adhesive tape, crease andscratch resistance.

It is seen that the magnetically coated structures disclosed herein areuseful in the recording of information of various natures includingaudio, video and computer and other data for both preservation andreproduction of said data. By properly manipulating the ingredients, andthe ratio of one to another, which tasks can be accomplished readily bythe artisan, the coating films prepared hereunder may be employed forany type of data collection and reproduction. The compositions employedin accordance with the invention are independent of the base orsubstrate upon which they are coated. Thus any substrate such aspolyethylene terephthalate (Mylar®) cellulose acetate, nylon, among theplastics; and aluminum, copper, and other non-magnetic alloys among themetals. The foregoing examples are merely illustrative of my inventionand the invention should not be limited to those described. For exampleas new commercial latices become available many of them may also be usedin my invention. Thus is is possible to consider future latices ofpolycarbonates or polysulfones as applicable to this invention.

The trademarks referred to above are believed to be of the followingchemical compositions as best discernable from literature available tothe public:

1. Rhoplex E-358 an acrylic latex produced by Rohm and Haas.

2. UCAR-366 a vinylacetate-butyl acrylate latex produced by UnionCarbide

3. UCAR-503 an acrylic copolymer latex produced by Union Carbide

4. Impranil DLH a polyester-polyurethane polymer dispersion produced byMobay Chemical

5. Witcobond W-234 an aliphatic polyurethane dispersion produced byWitco Chemical

6. Goodrich Hycar latices such as 26091, 26106, 26138 and 1577 areacrylic polymer and copolymer latices of high Durometer hardnessproduced by B. F. Goodrich

7. Aerosol OT is a salt of a succinosulfate ester produced by AmericanCynamide

8. Mazamide 80 and 20 are fatty acid amides of diethanol amine producedby Mazer Chemical

9. MAFO 13, MOD 1 is a salt of an amphoteric amino acid surfactantproduced by Mazer Chemical

10. Nopcosperse 44 is a salt of a polyacrylic acid produced byDiamond-Shamrock

11. Gafac RE-610 is a surfactant produced by GAF Corp.

12. Silwet L-7600 and L-7602 are silicone surfactants produced by UnionCarbide

It is seen that the above latices can provide soft or relatively hardcoatings. By relatively hard I mean a durometer A hardness of greaterthan 90.

Since certain changes may be made in the above examples withoutdeparting from the scope of the invention involved, it is intended thatall matter contained herein should be interpreted as limiting.

I claim:
 1. A water based dispersion system for coating magneticparticles onto a substrate comprising:water sufficient to form adispersion, at least one adhesive plasticizer (Additive A), at least oneadhesive polymer (Additive B), at least one surface active agent, anoptional dispersing agent, at least one polymeric latex capable ofbinding magnetic particles into a coating, wherein Additive A is of thegeneral formula

    Y--CO--NX--CH.sub.2 --P

and Y is selected from the group consisting of H, an akyl group of C₁-C₄, an alkylene group of C₂ -C₃, an ethanol, propanol or isopropanolgroup, a 2-3 carbon ether group, and a C₁ -C₃ haloalkyl group, said haloselected from the group consisting of being chloro or fluoro, andwherein Additive B is a water soluble or dispersible polymer which wasformed by the copolymerization of a first component which has at least5% of its monomer constituents being derived from a monomer selectedfrom the group consisting of acrylamide and methacrylamide, and thebalance being a second component of one or more vinyl monomerscopolymerizable with said first component, thereby having yielded anamido copolymerizate, said amido copolymerizate having been furthercondensed with formalhehyde to the extent of from 5% to 95% of the amidegroups, said condensed amido copolymerizate having been still furthercondensed with a member selected from the group consisting of apolyhydroxy aromatic compound, an amido hydroxy aromatic compound, or adiamino aromatic compound, and sufficient magnetic particles of a sizesuitable for dispersion as a magnetic film upon a substrate.
 2. As a newcomposition for use in the magnetic particle coating of substrates froma water based composition, which composition comprises a water solubleor water dispersable mixture of Additive A and Additive B, whereinAdditive A is at least one adhesive plasticizer and Additive B is atleast one adhesive polymer,wherein the adhesive plasticizer Additive A,is a condensation product of N-hydroxymethyl acrylamide with a solublecompound selected from the group consisting of polyhydroxyaromaticcompounds, aminophenols and aromatic diamines; and wherein the adhesivepolymer, Additive B, is a condensation product of polymers andcopolymers of acrylamide with a partial molecular equivalent offormaldehyde, followed by further condensation with a soluble compoundselected from the group consisting of polyhydroxy aromatic compounds,aminophenols and aromatic diamines.
 3. In the composition of claim 2wherein Additive A is a condensation product of N-hydroxymethylacrylamide with a polyhydroxy aromatic compound, wherein saidpolyhydroxy aromatic compounds are selected from a group consisting ofresorcinol, catechol, hydroquinone, hydroxyethyl resorcinol and n-butylcatechol.
 4. In the composition of claim 2 wherein Additive A is acondensation product formed from the reaction of N-hydroxymethylacrylamide with aminophenols, said aminophenols being selected from thegroup consisting of o,m and p-aminophenol, the methyl aminophenols andthe hydroxyethyl aminophenols.
 5. In the composition of claim 2 whereinAdditive A is a condensation product formed from the reaction ofN-hydroxymethyl acrylamide with aromatic diamino compounds, such membersof the diamino aromatics being selected from the o,m and p-diaminobenzenes, the o,m and p-diamino toluenes and the various isomers of thehydroxyethyl diamino benzenes.
 6. In the composition of claim 3 whereinAdditive B is a condensation product of polymers and copolymers ofacrylamide with a partial molecular equivalent of formaldehyde, followedby a further condensation with a soluble compound selected from thegroup consisting of a polyhydroxy aromatic compound selected from thegroup consisting of resorcinol, catechol, hydroquinone, hydroxyethylresorcinol and n-butyl catechol.
 7. In the composition of claim 3wherein Additive B is a condensation product of polymers and copolymersof acrylamide with a partial molecular equivalent of formaldehyde,followed by further condensation with a soluble aminophenol compoundselected from the group consisting of o,m and p-aminophenol, the methylaminophenols and hydroxyethyl aminophenols.
 8. In the composition ofclaim 3 wherein Additive B is a condensation product of polymers andcopolymers of acrylamide with a partial molecular equivalent offormaldehyde, followed by further condensation with a soluble aromaticdiamine selected from the group consisting of o,m and p-diamino benzene,diaminotoluenes and the hydroxyethyl diaminobenzenes.
 9. A water baseddispersion system for coating magnetic particles onto a substratecomposition as in claim 1 wherein there is water sufficient to form adispersion of the magnetic particles with proportional amounts ofAdditives A and B and a commercial aqueous latex capable of bindingmagnetic particles.
 10. The system as in claim 9 wherein the commerciallatices are chosen to provide a relatively soft coating and whichlatices are selected from the group consisting of acrylic copolymers asrepresented by the commercial designations Rhoplex E-358, UCAR 366 andUCAR
 503. 11. The system as in claim 9 wherein the commercial laticesare chosen to provide a relatively hard coating and are selected fromthe group consisting of acrylic copolymers and polyurethane aqueousdispersions.
 12. In the compositions of claim 11 wherein the laticesproviding relatively hard acrylic copolymers are compositions bearingthe commercial description Hycars 26091, 26106, 26138 and
 1577. 13. Inthe composition of claim 11 wherein the polyurethane dispersions arecompositions bearing the commercial designations Witcobond W 234 andImpranil DLH.
 14. In the system of claim 1 wherein the surface activeagent is a mixture of a higher alkyl succino sulfate and a fatty acidamide of diethanolamine.
 15. In the system of claim 1 wherein thesurface active agent is a mixture of a fatty acid amide ofdiethanolamine and a salt of a complex amphoteric aminoacid.
 16. In thesystem of claim 1 wherein the surface active agent is one member of thegroup consisting of a mixture of a higher alkyl succino sulfate and acomplex organic phosphate ester acid and a surface active siliconecompound.
 17. In the system of claim 1 wherein the composition furtherincluding a dispersant which is a low molecular weight salt ofpolyacrylic acid.
 18. A water based dispersion system for coatingmagnetic particles onto a substrate comprising:I. water sufficient toform a dispersion, II. a magnetic iron oxide suitable for audio, videoand data recording, III. an adhesive plasticizer, Additive A, preparedby the combination of N-hydroxymethyl acrylamide with a compound Y, IV.an adhesive binder Additive B, which binder is prepaid by thecondensation of polymers and copolymers of acylamide with about 0.25molecular equivalent of a compound Y; wherein said compound Y isselected from the group consisting of polyhydroxy aromatics, the aminophenols and the aromatic diamines V. a commercial latex selected fromthe soft and hard coating polymers of acrylic copolymers andpolyurethanes, VI. a surfactant VII. an optional dispersant.
 19. A waterbased dispersion for coating magnetic particles onto a substratecomprising:water sufficient to form a dispersion with all of thefollowing: a high coercivity magnetic iron oxide, an adhesiveplasticizer prepared by the condensation of N-hydroxymethyl acrylamidewith an equivalent amount of resorcinol: an adhesive binder prepared bythe condensation of a polyacrylamide with one-fourth the molecularequivalent of formaldehyde followed by further condensation withcatechol, a polyurethane latex, a surfactant mixture of an oleic acidamide of diethanolamine and a salt of a complex amphoteric amino acid, adispersant of a salt of a low molecular weight polyacrylic acid and anoptional anti-foam agent.
 20. The composition of claim 3 furtherincluding a water dispersible latex capable of binding magneticparticles.
 21. A magnetic tape composition suitable for coating as inclaim 1 comprising about 5.5 grams of magnetic ferrite, about 4 mlwater, about 0.35 ml of a resorcinol based Additive A;about 0.8 ml ofmeta-aminophenol based Additive B; a polymeric latex, a dispersingagent, a surface active agent, and additional water for processing. 22.In the composition of claim 21 wherein the Additive A and the Additive Bare each meta-toluene diamine based.